The attack took place in the Sangin district of Helmand province where U.S., British and Afghan forces have been battling Taliban militants.

In western Afghanistan, a U.S. soldier died when a NATO patrol hit a hidden bomb after thwarting insurgents who were planting roadside bombs, NATO said in a statement.

The death brings the U.S. death toll in Afghanistan this month to seven.

"I wish to convey my most sincere sympathies to this hero's loved ones as they attempt to cope with their tragic loss," said spokesman Brigadier-General Eric Tremblay.

The service member's name was withheld pending notification of next of kin.

The violence came a day after the arrival of new NATO Secretary General Anders Fogh Rasmussen in Afghanistan for meetings with Afghan President Hamid Karzai, U.S. Gen. Stanley McChrystal, other leaders and troops.

Afghanistan will hold a presidential election later this month, with Karzai among the dozens of candidates.